Ignition composition



Patented Oct. 11, 1949 rom'rroN COMPOSITION Willia'm Dl l'lrevorrow, Hometown, Pa., assignor to Atlas-Powder Company, Wilmington, DeL, a

,- corporation of Delaware Application November 19, 194.6, Serial No. 710,939

No Drawing.

'7 Claims.

' The present invention-relates" to compositions of matter for the preparation of ignition devices. An object of the present invention isthe provision .of a composition of matter of the type specified which does not tend to'jell;

Another object of the invention is the provision of a composition of matter of the type specified which has desirable viscosity characteristics.

Other objects of the invention will be apparent from the following description. Ignition devices are customarily prepared by surrounding heatable elements such as an electric bridge wire with a coating composition carrying a heat-sensitive ignition compound.

One common type of ignitenis the bridge plug type used in some forms of electric detonators. A bridge plug comprises a plug of material separating two leg wires connected'together by a fine, high resistance, bridge wire. A coating composition admixed with an igition compound, is spread around the bridge Wire. The spreading is called buttering because of the viscous consisten'cyof the composition containing the ignition compound. The buttered material dries hardon evaporation of the solvent, and subsequent heating of the bridge wire as by passage of an electric current fires the ignition material with the production of a burst of name."

' Another form of igniter, also commonly-used in detonators, is the electric match which is composed of two insulated metal plates or foils connected together by a bridge wire and dipped in a coating composition containing an ignition compound. The dipping operation forms, around the bridge wire, a drop of ignition material which hardens on drying. Electric matches also may be fired by passage of an electric current through the bridge wire.

While many different materials are used for ignition compounds, lead salts of nitrophenols have been found particularly desirable in many instances. Examples of lead nitrophenols which are particularly useful in accordance with the present invention are lead styphnate, monobasic lead 4:6 dinitro-ortho-cresylate, monobasic lead picramate, monobasic lead 3:5 dinitro-benzoate,

lead nitrato-bis-basic-lead 4:6 dinitro-orthocresylate, normal lead 2 nitro-resorcinate and monobasic lead 2 nitro-resorcinate.

The coating composition which is used to carry the ignition compound is usually of the lacquer type composed of a highly combustible nitrocarbohydrate such as nitrostarch or nitrocellulose and a volatile solvent such as esters of the type of butyl acetate and amyl acetate, aromatic hydrocarbons such as benzene, and the like. Depending on the viscosity or volatility characteris-, tics desired, different solvents or mixtures of solvents are used as is well understood in the art.

, A difficulty which has been found to occur when lead salts of nitrophenols are used in lacquers of this type has been that the composition tends to set up into a gel prior to use, and in a gel form it is difficult to apply.

According to the present invention it has been discovered that compositions of the present type do not exhibit this gelling phenomenon when a monohydric alcohol containing less than six carbon atoms, or a mixture of such alcohols, is in cluded in them. Usually the lower aliphatic alcohols such as methyl, ethy1, butyl and iso-propyl alcohols are most readily available and are preferred. However, other alcohols such as iso-amyl and tetrahydro-furfuryl alcohol are quite satisfactory. The alcohols may be used as the sole solvents, but it is usually preferred that they be used'in proportions up to about 20% by volume based on the total volume of the composition excluding ignition compounds. The minimum amount of alcohols necessary completely to inhibit gelling will depend somewhat on the particular alcohols and on the other ingredients of thecomposition.

The following examples are illustrative of specific embodiments of the invention:

Example 1 A lacquer was made up by adding 1 ounces of nitrocotton to one gallon of amyl acetate. 9.0 milliliters of this lacquer were added to 4.1 grams of monobasic lead, 3:5 dinitro-ortho-cresylate. Upon mixing these two materials a gel was produced. To this gel was added 0.9 milliliter of denatured ethyl alcohol (ethyl alcohol containing 5% of methyl alcohol). Upon mixing, the gel broke down producing a paste of desirable consisterniy for producing match heads by dipping. Electric match bases were dipped in this composition; the resulting head or head of ignition composition was dried; the match heads were given a protective coating dip of a 6 ounce ether-alcohol nitrocotton lacquer and a second dip of an amyl acetate nitrocotton lacquer; and as finished, the matches were found to be entirely satisfactory.

Examples 2 through 6 Six batches of ignition composition were each made by stirring 9.0 milliliters of the lacquer used in Example 1 with 3.0 grams of lead nitrato-bisbasic-lead 4:6 dinitro-orthocresylate for 5 to 10 minutes. To each of these batches difierent al- 3 cohols were added in 0.5 milliliter portions followed by 3 minutes of mixing until the gelled condition was relieved, as evidenced by a smooth mixture suitable for the preparation of match heads by dipping. The alcohols employed and the amounts found necessary in each of these examples are tabulated below:

Example Alcohol iso-amyl tetrahydro-furluryl Compositions of the present invention may be in which the monohydric alcohol is methyl alcohol.

also used for buttering operations as described;

above.

What is claimed is:

1. A composition of matter comprising nitrostarch, a volatile solvent therefor, an anti-gelling agent comprising a monohydric alcohol containing less than 6 carbon atoms, and an ignition compound selected from a group consisting of lead styphnate, monobasic lead 4:6 dinitro-orthocresylate, monobasic lead picramate, monobasic lead 3:5 dinitro benzoate, lead nitrato-bis-basiclead 4:6 dinitro-ortho-cresylate, normal lead 2 nitro-resorcinate and monobasic lead 2 nitroresor'cinate, said anti-gelling agent being contained in an amount suflicient to prevent gelling of the composition but not in excess of about by volume of the composition exclusive of ignition compound.

2. A composition of matter comprising nitrocotton, a volatile solvent therefor, an anti-gelling agent comprising a monohydric alcohol containing less than 6 carbon atoms and an ignition compound selected from the group consisting of lead styphnate, monobasic lead 4:6 dinitro-orthocresylate, monobasic lead picramate, monobasic lead 3:5 dinitro-benzoate, lead nitrato-bis-basiclead 4:6 dinitro-ortho-cresylate, normal lead 2 nitro-resorcinate and monobasic lead 2 nitroresorcinate, said anti-gelling agent being contained in an amount sufficient to prevent gelling of the composition but not in excess of about 20% 6. A composition of matter comprising amyl acetate,, ethyl alcohol, nitrocotton, and monobasic lead 3:5' dinitro-ortho-cresylate, said ethyl alcohol being contained in an amount sufficient to preventgellingof the composition, but not in excess of about 20% by volume of the composition exclusive of ignition compound.

-'7. A composition of matter comprising a combustible nitrocarbohydrate, a volatile solvent therefor, an anti-gelling agent comprising a monohydric alcohol containing less than six carbon atoms, and an'ignition compound selected REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,194,095 Swope Aug. 8, 1916 2,159,229 Rubens'tein May 23, 1939 FOREIGN PATENTS Number Country Date 483,492 Great Britain Apr. 20, 1938 703,534

France Feb. 9, 1931 

